ES5 Array.map() function for #React Quick Notes.

1. Array.map() function iterate through every element in array only once.
2. It do not alter original array but return new array when called.

For example.

let myArray = [1,2,3];

var newArrayMultipleOfOldArray = myArray.map(x=>x*2);
console.log(newArrayMultipleOfOldArray );

//Below reference is from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

// Arrow function
map((element) => { /* … */ })
map((element, index) => { /* … */ })
map((element, index, array) => { /* … */ })

// Callback function
map(callbackFn)
map(callbackFn, thisArg)

// Inline callback function
map(function(element) { /* … */ })
map(function(element, index) { /* … */ })
map(function(element, index, array){ /* … */ })
map(function(element, index, array) { /* … */ }, thisArg)